African swine fever virus (ASFV) continues to spread in Europe with a recent jump to the south in Italy (Calabria) as well as outbreaks in Bosnia-Herzegovina and bordering Croatia. Vector control and measures such as quarantine , biosecurity, animal movement control as well as emergency depopulation are some of the main strategies for disease control. Vaccines are being deployed in some countries (Vietnam, DR, Phillipines) but these vaccines would not likely be used in Canada as they can’t be differentiated from field virus infection. We know that ASFV is very stable and infectious over long periods of time especially at low temperatures. The survival of ASFV in animal feed, bedding, infected carcasses and underlying soil at various temperatures have been well documented. One piece of the survival puzzle that has not been documented is the survivability and infectivity of ASFV in groundwater at various temperatures. These UK and Irish researchers wanted to study the stability and infectivity of ASFV in environmental samples of river water. River water was chosen for the incubations as it was considered the most appropriate matrix to determine ASFV survival in the natural environment rather than in laboratory grade distilled water. The researchers evaluated a cell culture-adapted ASFV strain BA71V by plaque assay after incubation of the virus within various Thames River water samples at three different environmentally relevant temperatures (4 °C, 15 °C, and 21 °C) over the course of 42 days.
The researchers found the following:
- ASFV can remain stable and infectious when maintained at 4 °C in river water for more than 42 days
- ASFV can remain stable and infectious when maintained at 15 °C in river water for 28 days
- ASFV can remain stable and infectious when maintained at 21 °C in river water for 14 days
- Take Home Message:
- Understanding the survivability of ASFV in river water (42+ days at 4 °C) can support disease control recommendations for virus inactivation through disinfection and quarantine downtimes.
- The researchers also theorized that the dumping of ASFV infected carcasses in waterways was potentially problematic as the pig origin organic materials in the carcass could further enhance the survival times of ASFV in ground water. The illicit dumping of infected carcasses into waterways has been documented in many ASFV affected regions.
Source : Swine Web